interferens

Interferens, or interference, is a phenomenon in which two or more waves superpose to form a resultant wave whose amplitude is determined by the phase relationship between the contributing waves. It occurs when waves overlap in space and time and is most evident for waves with a well-defined phase and frequency, such as light, sound, or water waves.

Interference patterns arise when the Waves are coherent, meaning their phase difference is predictable over time. The key factors are path difference and wavelength. If the phase difference leads to alignment of crests, constructive interference occurs, increasing the amplitude. If it leads to alignment of a crest with a trough, destructive interference occurs, reducing the amplitude or canceling the wave.

In optics, interference produces bright and dark fringes, such as in a double-slit experiment. In acoustics, it affects sound volume and timbre in space. Interference can be described mathematically by the resultant intensity I = I1 + I2 + 2 sqrt(I1 I2) cos(phi), where phi is the phase difference between the waves. For equal amplitudes, I = 4 I0 cos^2(phi/2). If the waves have random phases, stable interference patterns do not form and the average intensity is simply the sum of the individual intensities.

Interfering waves are exploited in interferometers to measure tiny changes in distance, refractive index, or wavelength. Notable devices include the Michelson interferometer and the Fabry-Pérot etalon. Interference underpins applications in spectroscopy, holography, metrology, and the study of wave phenomena across physics.